1. Field of the Invention
The present invention relates to an image forming apparatus, a control method thereof, and a storage medium, and more particularly, to an image forming apparatus which includes an SSD as an auxiliary storage device and which is capable of preventing loss of data in the SSD caused by continuance of a power save state or a power off state, a control method thereof, and a storage medium.
2. Description of the Related Art
In recent years, an SSD (Solid State Drive) is more often used as the auxiliary storage device of an image forming apparatus. Compared with a conventional HDD (Hard Disc Drive), the SSD is superior from the standpoint of access time, heat generation, operation sound, impact performance, power consumption, and size.
Generally, an SSD has a plurality of flash memories, installed therein, in which data is saved. With the flash memory, data is saved or erased by electrons being injected into or ejected from a floating gate covered with an insulating material, and at this time, the insulating material has a high voltage applied thereto with the insulating material deteriorated, which causes data to be lost due to self-discharge after a predetermined period of time, that is, after a retention period (a data retention period).
For example, there is a report that, if an SSD used over a period of time specified by JEDEC (Joint Electron Device Engineering Council) is not energized, data in the SSD is unfavorably lost in three months. Also, due to densification of an integrated circuit used in the SSD, data in the SSD is possibly lost due to cutoff of power over a shorter period of time.
With recent power-saving trend, some image forming apparatuses are configured to de-energize the auxiliary storage device at the time of shifting from a normal state to a power save state. In a case where an SSD is used as the auxiliary storage device of such an image forming apparatus, the power save state having continued with the retention period of the SSD elapsed causes the data in the SSD to be lost. Also, when the power of the image forming apparatus is turned off, the auxiliary storage device is not energized, which incurs loss of data if the power off state continues over a long period of time.
Japanese Laid-Open Patent Publication (Kokai) No. 2013-47913 proposes an information processing apparatus that prevents loss of data from a non-volatile storage device by not writing in the non-volatile storage device when the life of the non-volatile storage device is near expiration. However, the proposed technique cannot prevent loss of data due to lapse of the retention period of an SSD.
Also, recent improved multi-functionality of the image forming apparatus allows software operating on the image forming apparatus to become complex with increased scale. Moreover, to use past application development resources, a highly portable application independent of the hardware is, in many cases, operated on a versatile OS installed on the image forming apparatus.
However, it is difficult to prevent loss of data in a non-volatile storage device of an image forming apparatus having a versatile OS, installed therein, on which an application not aware of hardware operates on the versatile OS.
The technique disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 2013-47913 aims to maintain data retention reliability of a non-volatile storage device by suppressing writing in the non-volatile storage device. However, with an image forming apparatus having a versatile OS, installed therein, on which a complex, large-scale application operates, it is difficult to maintain the data retention reliability of the non-volatile storage device (an auxiliary storage device such as an SSD). That is, maintenance of the data retention reliability requires to grasp all the behaviors of the complex, large-scale application, and to perfectly control access from the application to the auxiliary storage device, for example, to eliminate the amount of writing in the auxiliary storage device.
However, with an image forming apparatus having a versatile OS having a complex, large-scale application operating thereon a versatile OS, it is extremely difficult to perfectly control access from the application to an auxiliary storage device, that is, it is difficult to increase the data retention reliability of the auxiliary storage device such as an SSD of such an image forming apparatus.